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Questions tagged [blockchain]

This tag should be used for questions pertaining to the blockchain. The blockchain is a list of all transactions that have occurred using the Bitcoin currency. It consists of blocks which are linked to each other, and each block consists of transactions. DON'T USE THIS FOR THE SERVICE NAMED '...

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Is it posible to create a transaction output that can either be reddemed by privK of Addr A or by privK of Addr B AFTER certain blockheight?

I am thinking about how to secure your Bitcoin savings. One idea I had was to create sort of a "backup" address B for an address A which stores the bitcoins. So what I want to achieve is that you ...
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How to recover bitcoins from personal wallet app in android which is uninstalled?

I am using a bitcoin Non-deterministic wallet created by a private firm. In which there are few bitcoins worth 100$ Somehow I clear data of the android App, and Now all the memories related to my ...
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Is it safe to store user's secure pass-code in database with encrypted form while creating bitcoin wallet?

I would like to create a Bitcoin Wallet. Part of the process is to store public and private keys in encrypted form in server database. All keys I am storing is encrypted using user's passcode. 1) ...
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Why lightweight nodes are less secure?

as you know there is two main type of wallets: full node and light node I've read in some advice that just using full node for more security stuff and the next question is what is the type of ...
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After genesis generation I am getting txout.nvalue negative

Have you encountered the error - "txout.nvalue negative" when trying to mine the first block using the command "setgenerate true". I am stuck over there. This is on a PIVX fork.
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In the basic Wallet based in QT, How can i get by RPC the stored addresses and labels?

this question is for you to ask about the QT wallet, in the section to send coins, there is an address window, and it has the list of the stored addresses we save along the time. So using RPC, do you ...
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2answers
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Blockchain and anonymous data inside the chain

A Blockchain is often said to be a log of all transactions that were ever verified on a network. I understand that therefore a purpose could be to make sure that the records are not altered. If they ...
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UTXO are not being listed while they have conf over 100 (btcd + simnet)

I am using BTCD and while in Simnet, I generated 104 block (Best block : 104) But when I listed utxos, transaction from block 3 and 4 (which have 102 and 101 confirmations) don't be listed. So balance ...
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My BTC transaction is confirmed but not yet showing

i have enter the correct address as i read the QR code at that time it showed me in reciving payment done but not yet shown
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Idioms of use/ bitcoin heuristic

I already know the answer of a) part which is Alice. Can anybody help me in finding answer of b) part.
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Failing to create a new address to be used for receiving staking rewards whenever a generated block is accepted

Our problem is that we need to get a new address on each stake. What I've tried so far is: Generating a new address right before a block is accepted and try using it to receive the stakes, but that ...
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1answer
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What is single member blockchain?

I just heard about single member blockchains like quorum and hyperledger-fabric. So what does single member mean? Is this some kind of restriction or what?
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Rules of the mining pools for mining software and weight blockchain Litecoin

What rules must a mining software fulfill in order for a pool to allow mining with the ?, example of a pool please. How heavy is Liteco's chain of blocks at this moment or where can I consult it?
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1answer
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How to get my bit coin back

I have copied and sent bitcoin to the address that I have found on my blockchain wallet only to find out its not mine. So is there anyway I can get my bitcoin back?
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Blockchain-based DLT vs. Graph-based DLT

We may divide Distributed Ledger Technologies (DLTs) into the following types: (1) blockchain-based such as Bitcoin, Ethereum, Hyperledger etc. (2) Graph-based DLTs, where every block/vertex can ...
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Blockchain testnet Websocket

Please, how do I subscribe to blockchain testnet web-socket for an address. I seem to find that for livenet, any help?
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Bitcoin address switched and delay receiving money [duplicate]

I sent bitcoins to my Electrum wallet but they have not been shown after 12 hours. Why the delay? Now I see that my Electrum wallet has switched address on receiving the figs, does it matter?
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Question Regarding Send_to_many function of blockchain wallet api

I am using send to many function of blockchain wallet api and i am facing issue. when upto 20 transaction done then after i get error in terminal that 1538652825520 - error: ERR_PUSHTX ...
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Why my altcoin only generate wrong key (only with prefix 3)

I created and run an altcoin blockchain. It's seems everything is good besides all the keys produced by the blockchain are with prefix 3 (seems like all are p2sh). I have tried the past two weeks to ...
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Becoming Bitcoin wallet provider from scratch [closed]

I want to launch a bitcoin wallet service website for creating new wallets. And i want to provide a tool for user for importing their old wallets using public and private key. I know i can use some ...
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Transactions Uniqueness Verification

From what I gathered, to process a bitcoin transaction I basically create the transaction object locally, add my signature generated with my private key, then send this to a public node for it to add ...
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1answer
33 views

Solar Flare wipes all hard drives… What happens?

Imagine, for a moment, that a massive solar flare wipes out all hard drives on planet Earth. All hard drives are wiped clean and with them all records of the Bitcoin blockchain. Would we be able to ...
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1answer
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Is it secure to collect common public addresses under a wallet using BlockCypher Wallet API

I am working on an exchange platform with users having separate pair of public and private keys using blockcypher api. I encountered Blockcypher Wallet API, and it seems its a pleasant way of ...
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1answer
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Transaction in orphaned block question

This is a theoretical question. Assuming that a transaction (TX_A) with me on the receiving end gets added to the blockchain, I should be able to spend the amount I received. So I go on and spend it ...
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What is required to list market data from cryptocurrency? [closed]

I am trying to create a cryptocurrency market capitalization list similar to coinchangelly.com . Where could I obtain their APIs and how do I list much more coins than others?
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1answer
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When does a blockchain fork resolution happen?

I understand that the forks are resolved by largest proof-of-work etc. but when do the miners decide to resolve a fork? Is it a network consensus or do each individual miner resolve at their own pace?
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1answer
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Bitcoin protocol allows a chain to be undone by a longer chain

In Mastering Bitcoin, page 196, it says "While the protocol always allows a chain to be undone by a longer chain and while the possibility of any block being reversed always exists, the probability of ...
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1answer
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Permissioned blockchains on EVM: are these private ledgers os it all on ETH main net?

Private blockchains using EVM: is this really the equivalent of the library of tools in hyper ledger or do these blockchains run on the public main net?
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Bcoin: Trouble With bitnodes Help!

Hi i got a trouble on my bcoin node and im very confused i followed the instruction on this page .http://bcoin.io/guides/install-linux.html. but when im going to verify my node in bitnodes it gives me ...
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When I create a new block, will it be added to an existing blockchain, or form a new one? [duplicate]

i Just Want to know that as we are creating a new block that is first block so it will connect to the existing blockchain in the world or it will create a new blockchain?
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1answer
33 views

Create wallet address on user registration for trading platform

I am creating a crypto-trading platform . I wanted to know how to create wallet address dynamically for all new registered user and also create new address for every transaction. I am using bitcoind ...
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2answers
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is every Block of blockchain is connect to each other? [duplicate]

like as we create a new block , so it will connected to existing Blockchain or it will create a new blockchain?
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Setting up node, no connection when announce ip address to peers

I want to announce my host name when running node. When I set nxt.myAddress=hostname or IPaddress, there are no connection to peers. But when I keep it empty everything is fine.
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Leader election-based Blockchains public?

Consensus protocols such as those of Tendermint, Red Belly Blockchain or Algorand can be of great help when dealing with the problem of Finney attacks, and similar sorts of abusing of excessive 'thing'...
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1answer
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Is PBFT a consensus algorithm?

Can we consider PBFT (Practical Byzantine Fault Tolerance) as a consensus algorithm ? And if yes, How does it work? And is it similar to other consensuses such as PoW, PoS or PoA ? Or it is totally ...
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1answer
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Block Chain length/size may one day get unwieldy to compute

Is it possible that the length of the existing block chain will one day become unwieldy to compute? Would it make more sense that the chain would somehow be rolled up like normal bank ledgers do with ...
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1answer
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IBM Blockchain platform specifications

So I saw an ad for IBM's blockchain platform, specifically the campaign they have to "turn plastic into money" by way of exchanging recyclable materials for digital tokens. I was just wondering if ...
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1answer
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Why the block's order in blockxxxxx.dat is different from blockchain.info

I parsed the block00000.dat using python code: class BlockFile: def __init__(self, block_filename): self.block_filename = block_filename self.blockchain = open(block_filename, 'rb', ...
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How many nodes would one typically check to determine the longest chain?

Before posting a solved block to the longest chain, how many nodes would one need to check before making sure that the longest chain was found?
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1answer
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how to validate testnet and mainnet bitcoin address via online api or offline for Android App?

I would like to know web api provider to validate Mainnet & Testet3 Bitcoin Address. How to validate a Bitcoin address is a real one? Validate bitcoin address from android application Gone ...
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2answers
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Any idea how to download a small part of the chain for testing purposes?

I am experimenting with Python and Rust libraries on my laptop. I don't actually want to get a node going on it and download the full chain; I just need some blocks to play with. I want to keep my ...
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How much electricity would state-of-the-art hardware burn to solve current proof of work problem for one block? [duplicate]

I am wondering what would be the energy cost to create a fake blockchain that could fool a victim who had no access to any other information, except the current block difficulty level. Take the ...
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1answer
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How to protect the latest block in block chain be tampered?

We know for each block in block chain, it has the previous block header hash which make the block be tampered become difficult. If the block is tampered, then all blocks after this tampered block need ...
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1answer
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Does P2SH unlocking script only consist of operants?

I have a question about the P2SH unlocking script. Can I put common operants and operators in the P2SH unlocking script? And if yes, how can I create such script? e.g. unlocing script: <sig1> &...
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How much data does it take to prove a given transaction exists on the blockchain?

As I understand the SVP protocol, a client can be reasonably certain that a transaction has been accepted on the blockchain if they know it is a member of a certain block, via the Merkle path, and a ...
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Can you explain to me how this transaction work?

I was looking at bitcoin rich list and found binance cold wallet For this transaction in particular https://www.blockchain.com/btc/tx/afb6523e4f5f060a076dcc2f8e5eb7a1aa58a3831456c62da946e2b5a41c24f0 ...
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1answer
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How come Merkle tree is more efficient when tree branches are not stored in blockchain?

Suppose we have 8 transactions in a block X as follows and we know every node's hash value of the whole Merkle tree (that is, including intermediary nodes such as 45). Then if someone claims ...
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How to convert Satoshi to bitcoin? [duplicate]

hi people just i am join on this site.can anyone Help by telling me how to convert Satoshi into bitcoin?
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January 19th, 2038: RIP Unix Timestamps

Is there a plan in place for when the inevitable 32-bit overflow of Unix timestamps occurs? How much will this impact existing blocks that are timestamped with Unix Epoch times?
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How to display a list of incoming bitcoin Transaction history in my own wallet?

I have gone through various references including How to get a history of incoming and outgoing transactions for a certain address? Fetch list of transaction where i have received the bitcoin? I am ...